Cyrus IMAP Server, version 2.4

IMAP (Internet Message Access Protocol) is an Internet
standards-track protocol for accessing messages (mail, bboards,
news, etc). The Cyrus IMAP server differs from other IMAP server
implementations in that it is generally intended to be run on
sealed servers, where normal users are not permitted to log in. The
mailbox database is stored in parts of the filesystem that are
private to the Cyrus IMAP system. All user access to messages is
through the IMAP, POP3, KPOP or NNTP protocols.

The private mailbox database design gives the server large
advantages in efficiency, scalability, and administratability.
Multiple concurrent read/write connections to the same mailbox are
permitted. The server supports access control lists on mailboxes
and storage quotas on mailbox hierarchies.

The Cyrus project is the implementation of IMAP servers by the
Carnegie Mellon University Computing Services Department. Over the
next few months, we will be releasing components of this server,
which will provide better mail security and easier mail
administration.